Walking the dogs this morning on Father Hooper Field @ Chesterfield and Harford Road, I looked up and saw the most beautiful cloud formations. I think these are Altocumulus clouds. They are mid-level clouds, spanning from between 6,000 feet up to 20,000 feet into the atmosphere. They are composed of water droplets, unless it’s cold enough to freeze the droplets into ice crystals.

Altocumulus clouds usually form by convection in an unstable layer aloft, which may result from the gradual lifting of air in advance of a cold front. The presence of altocumulus clouds on a warm and humid summer morning is commonly followed by thunderstorms later in the day. I got this information from the Dept. of Atmospheric Sciences @ the Univ. of Ill., Urbana-champaign.